ASHRAE Journal - May 2023 - 45

TECHNICAL FEATURE
with thermal bridging requirements.
June's article will further discuss
thermal bridging.
2. Insulated metal panels (IMP):
Adds a defi nition for IMPs and new
requirements specifi cally for IMPs.
3. Cold-formed steel-framed roof
and wall compliance calculations:
Adds a new method for calculating
the U-factor of cold-formed steel roof
" Standard 90.1 continues to adapt
to the needs of the building industry
and provide a cost-effective energy
effi ciency standard that benefi ts
stakeholders and society as a whole. "
-Don Brundage,
Chair of SSPC 90.1, 2020-2023
and wall assemblies using the ANSI/AISI S250 Standard.
4. Wall solar refl ectance: Adds minimum wall solar
refl ectance requirements for certain climate zones.
5. Air leakage: Revises air leakage requirements in
a number of ways, including lower air leakage testing
threshold, revised test and measurement requirements
and revised performance compliance requirements.
6. Roof replacements: Specifi es requirements
for cases where the existing roof structure does not
allow insulation requirements to be met during roof
replacements.
7. Envelope commissioning: Relocates requirements
as described on page 49 for consistent
organization throughout the standard.
8. Envelope backstop: Limits the
amount of envelope performance
that can be traded off in performance
compliance paths (Section 12 and
Appendix G).
Insulated Metal Panels
Standard 90.1-2022 has added specifi
c requirements for IMPs in several
sections of Section 5 and Appendix
A. IMPs were not previously recognized
by Standard 90.1; therefore,
a product defi nition was added to
Section 3, Defi nitions, of the standard.
These changes were introduced in
Addendum cg, which was approved by
the 90.1 SSPC in July 2022.
IMPs are factory-made composite
panels formed by bonding two separate
metal skins to an insulative core
capable of transferring stress between
the skins, creating a rigid two-way
slab. The metal skins are formed into a
variety of joint confi gurations, allowing
use as either a roof or wall panel.
In either case, they may be used as
exterior cladding or provide a host
surface for traditional roof or wall
cladding materials. Their rigidity
allows them to meet the span requirements
for a variety of framing systems
and spacing. IMPs are approved for
use in exterior roof or wall construction
as well as interior partitions through common
third-party certifi cation agencies.
Although IMPs have been used in building construction
for 40 years, they were not specifi cally recognized in
building codes until recently. While IMPs were originally
designed for use in cold-storage facilities, increased
stringency of envelope requirements in building energy
standards has made them practical in other applications
and has resulted in a large growth in the number of
manufacturers and gross volume.
Depending on how IMPs are implemented for a given
project, they may be viewed as a building material,
New TPS, New Paths
Along with a brand-new mandatory section, Section 11-Additional Effi ciency
Requirements (aka Energy Credits) , the latest version of the standard integrates nearly 90
new addenda. Notably, the Title, Purpose, and Scope (TPS) of the standard has also been
expanded, and now includes " sites. " This expands the scope of the standard to include not
just the building but also equipment that may be not be directly associated with the building
(for example, parking lot lighting not connected to the building electrical service). Under the
new TPS, users can achieve more credit for on-site renewable energy production beyond
what's directly attached to the building. It also means that energy use associated with the
exterior and parking areas of the building must be considered.
The committee has also added four new appendices supporting technical content in the
main standard. These are: 1) Appendix I-alternatives to energy cost-based compliance, 2)
Appendix J-performance curves for chillers for use in modeling, 3) Appendix K-Informative
Figures in support of the thermal bridging criteria and 4) Appendix L-a mechanical system
component trade-off method.
Standard 90.1-2022 now contains a discipline-specifi c trade-off compliance path for each
of the major building components (envelope, lighting and mechanical). They are contained in
Appendix C for envelope, Appendix L for mechanical systems and Section 9.5.2 for lighting.
Each of these specialized trade-off methods could be used in the future to establish incentive
programs related to industry sectors or to help establish contractual requirements within the
architecture, engineering and construction (AEC) industry.
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